The treatment of bone fractures in craniomaxillofacial regions generally proceeds by reducing the fractured bone to its anatomically correct position, and thereafter fixing the bone in place. This procedure is known as an open reduction/internal fixation or "ORIF". In an ORIF, the bone may be fixed in place either by interosseous wiring or by the technique of miniplate (or bone plate) osteosynthesis. See Greenberg, A. M., editor Craniomaxillofacial Fractures: Principles of Internal Fixation Using the AO/ASIS Technique, Springer Verlag, New York (1993). In either case, holes must be drilled into the bone for receiving the interosseous wire or screws for holding the bone plates to the bone.
FIG. 1 shows a fractured mandible. The mandible M has a fracture F. The patient's skin S is shown in cutaway view. The mandibular nerve N runs through the mandible M and exits into the skin S at an anterior portion of the mandible, where it becomes the mental nerve ME, which is a delicate structure. The fractured mandible is treated with an ORIF procedure. The present invention is explained with respect to bone plate osteosynthesis, but a person skilled in the art will readily understand that the disclosure is equally applicable to interosseous wiring.
FIGS. 2 and 2A show a greatly enlarged bone plate P useful in the treatment of mandibular fractures. Numerous different configurations of the bone plate may be used depending on the size and shape of the fracture and bone structure to be reduced. The bone plate P is just one example of a suitable bone plate. The bone plate P consists of a chain-like body 41 having holes 42 therein. Each of the holes 42 is countersunk with a beveled edge 43 so that the holes 42 are adapted to receive surgical screws (not shown) and to retain the reduced bone in place until the bone heals. The bone plate holds the bone structure together so that it can heal.
An exemplary prior art intraoral (i.e., through the mouth) mandibular ORIF procedure is described as follows. As shown in FIG. 3A, a mandible M has a fracture F. The patient's skin S and tongue T are also shown. An incision SI is made through the patient's cutaneous region near the fracture F. A second incision, referred to here as the oral incision OI, is made in the buccal vestibule. The oral incision OI is generally V-shaped and runs parallel to the mandible M, as shown in FIG. 3B. Care is taken to locate and preserve the mental nerve. The, presence of the mental nerve at the anterior portion of the mandible M confines the area that the surgeon can access. Thus, the surgeon is confined to a small space in which to operate and accommodate surgical instruments.
As shown in FIG. 3A, two right angle retractors LR retract the mouth so that the fracture may be viewed. As seen in FIG. 3C, the retractors LR pull the oral incision OI anteriorly and posteriorly (indicated by the opposing horizontal arrows on the retractors LR), causing tension in the V-shaped oral incision which tends to pull the lateral aspects towards each other (indicated by the vertical arrows), thus tending to limit the surgeon's access to the incision.
The mandible is reduced to its anatomically correct position. This typically requires a retractor to access the fracture F. After the mandible is successfully reduced, the bone should be fixed in its proper position to heal. This is typically done with either interosseous wiring or bone plate osteosynthesis. This requires drilling holes in the mandible. This typically requires (1) retracting the tissue from the mandible to view the surgical area; (2) holding a bone plate in position across the fracture; (3) holding a drill depth guide to prevent drilling too deeply, or through, the mandible; and (4) operating the drill.
FIG. 3D illustrates how a conventional intraoral mandibular fixation is performed using the miniplate osteosynthesis technique. A trocar or cannula T is inserted into the incision SI. A bone plate P is positioned across the fracture, typically by one of (1) a surgical assistant who introduces the plate P through the patient's mouth and holds the plate in position with a surgical instrument such as a clamp; (2) holding the plate in place on the tissue below; or (3) sitting the plate on the retractor's base. The surgeon then inserts a drill through the trocar T in incisions SI, OI into alignment with a hole in the bone plate P. Once aligned, the surgeon drills a hole into the bone and then screws a screw into the hole in the bone plate P, thus, affixing the bone plate P to the mandible M. Alternatively, a threaded opening may be tapped in the bone prior to the introduction of the screw. In such a case, a tap is applied to the hole drilled into the bone before the screw is applied. At least one screw is placed on each side of the fracture in order to stabilize the bone. No retractor is located behind the mandible during the fixation.
This procedure requires three or more "hands" to perform; that is, two hands are needed to retract the mouth. The surgeon's hands are occupied with the trocar T and the drill, tap, or screwdriver. Additional hands may be needed to hold the plate P in position. This is disadvantageous for several reasons. First, the anterior and posterior retraction limits the surgeon's access to the oral incision, limiting the surgeon's view of and access to the surgical site. Second, the more "hands", instruments, or other obstructions in the area of the surgical site (here, at least two hands are needed to hold the retractors) reduces the surgeon's already limited visibility of the surgical site. There is the additional expense of a surgical assistant. Surgical assistants are relatively costly to the patient. Many insurance companies are searching for ways to reduce the expense of surgical assistants and some have eliminated insurance payments for the assistant altogether for certain procedures, leaving the expense of the assistant on the patient.
The prior art retractors and surgical methods, while useful, are not entirely satisfactory for the procedure described above.
Accordingly, it is an object of the present invention to provide a mandibular border retractor which reduces or eliminates the role of a surgical assistant in mandibular ORIF procedures.
A further object of the invention is to provide a retractor which improves the ease of an intraoral fracture reduction, thus reducing the likelihood of the patient undergoing an extraoral (transcutaneous) approach. The extraoral approach requires longer operating and hospitalization times and increases the likelihood of complications.
It is a further object of the present invention to provide a retractor that allows the surgeon to reduce the mandible, retract and view the surgical site, and hold the bone plate in position with a single hand, leaving the other hand free to operate surgical instruments.
It is yet a further object of the invention to provide a retractor which retracts the lateral aspect of an oral incision, thereby not placing tension on the incision which would limit the surgeon's access to surgical site.
It is yet another object of the present invention to provide a mandible retractor having an aperture through which retracts of the lateral aspect of the oral incision and also permits a drill guide, drill, or other surgical instrument to access the surgical site.
It is yet a further object of the present invention to provide a retractor which includes an integral surgical instrument holder.
It is yet a further object of the present invention to provide a clamp for grasping or reducing a mandible.